In a world where Apple's iPad and Android-powered tablets are ruling the roost, Hewlett-Packard is expected to launch two Palm Web OS-based Tablets today at a company event in San Francisco.

The company is set to launch a 7 Tablet called OPAL and 9-10 Tablet called TOPAZ. Both these tablets will likely support both GSM as wells as well as CDMA networks.

HP is expected to maintain the PALM momentum into the Mobile World Congress conference, which is being held in Barcelona in the middle of February 2011, wrote analyst Trip Chowdhry of Global Equities in a note to clients.

HP is also expected to launch two PALM Web OS smart phones, which will have much improved voice commands and unveil few Web OS based Printers, Chowdhry said.

HP is relying a lot on this event as it is expected to pitch Web OS against Apple's iOS, Google's Android, Windows 7 and RIM's QNX.

HP acquired Palm for a hefty $1.2 billion in April of last year to get its hands on the latter's Web OS platform, which has got rave reviews when it made its debut in 2009. But, the OS never took off due to poor marketing strategy.

HP's Web OS tablets are coming at a time when tablet shipments are expected to boom in the next two years. Recently IDC said it expects tablet shipments of 44.6 million units in 2011, with the U.S. representing nearly 40 percent of the total. In 2012, IDC forecasts worldwide shipments of 70.8 million units.

Google recently released Honeycomb (Android 3.0), which has been designed exclusively for tablets and Motorola says it plans to release its Xoom tablet in the first quarter of 2011. Xoom is the first tablet running on Android 3.0, also known as Honeycomb.

Meanwhile, competitors like Apple and Google have thousands of apps to woo users and stay in the market. In fact, the number of applications on Android Market currently stands at over 200,000, while Apple's app store has over 300,000.

Since HP bought Palm, it has attempted to make the web OS 2.0 appealing to developers as its software development kit (SDK) with the Mojo Framework allows developers to create apps in HTML, CSS and JavaScript, which appeals to the web developer community as they can create Web-native apps.

HP also offers a Plug-in Development Kit (PDK) that makes porting applications written for other platforms to Web OS possible. The PDK enables developers to use C and C++ alongside web technologies.

Android and iOS already have a host of developers writing apps for their tablets, so Web OS is more likely to compete directly with BlackBerry maker Research in Motion's PlayBook as its OS is also a new entrant in the market.